Semiconductor package

ABSTRACT

The invention provides a semiconductor package. The semiconductor package includes a semiconductor package includes a substrate having a die attach surface. A die is mounted on die attach surface of the substrate via a conductive pillar bump. The die comprises a metal pad electrically coupling to the conductive pillar bump, wherein the metal pad has a first edge and a second edge substantially vertical to the first edge, wherein the length of the first edge is different from that of the second edge from a plan view.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.61/616,040, filed on Mar. 27, 2012, the entirety of which isincorporated by reference herein.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a semiconductor package, and inparticular, to a high density flip chip package.

Description of the Related Art

In order to ensure miniaturization and multi-functionality of electronicproducts or communication devices, semiconductor packages are requiredto be small in size, multi-pin connection, high speed, and highfunctionality. Increased Input-Output (I/O) pin counts combined with theincreased demand for high-performance ICs has led to the development offlip chip packages.

Flip-chip technology uses bumps on chip to interconnect the packagemedia such as a package substrate. The flip-chip is bonded face down tothe package substrate through the shortest path. These technologies canbe applied not only to single-chip packaging, but also to higher orintegrated levels of packaging in which the packages are larger and tomore sophisticated substrates that accommodate several chips to formlarger functional units. The flip-chip technique, using an area array,has the advantage of achieving a higher density of interconnection tothe device and a very low inductance interconnection to the package.However, the increased amount of input/output connections of amulti-functional flip-chip package may induce thermal electricalproblems, for example, problems with heat dissipation, cross talk,signal propagation delay, electromagnetic interference for RF circuits,etc. The thermal electrical problems may affect the reliability andquality of products.

Thus, a novel high-density flip chip package is desirable.

BRIEF SUMMARY OF INVENTION

A semiconductor package is provided. An exemplary embodiment of asemiconductor package includes a substrate having a die attach surface.A die is mounted on die attach surface of the substrate via a conductivepillar bump. The die comprises a metal pad electrically coupling to theconductive pillar bump, wherein the metal pad has a first edge and asecond edge substantially vertical to the first edge, wherein the lengthof the first edge is different from that of the second edge from a planview.

Another exemplary embodiment of a semiconductor package includes asubstrate having a die attach surface. A die is mounted on die attachsurface of the substrate via a conductive pillar bump. The die comprisesa metal pad electrically coupling to the conductive pillar bump, whereinthe metal pad has a first length along a first direction and a secondlength, which is different from the first length, along a seconddirection from a plan view, wherein the angle between the firstdirection and the second direction is larger than 0 degrees and lessthan or equal to 90 degrees.

Yet another exemplary embodiment of a semiconductor package includes asubstrate having a die attach surface. A die is mounted on die attachsurface of the substrate via a conductive pillar bump. The die comprisesa metal pad electrically coupling to the conductive pillar bump, whereinthe metal pad has 2-fold rotational symmetry only from a plan view.

Still another exemplary embodiment of a semiconductor package includes asubstrate having a die attach surface. A die is mounted on the dieattach surface with an active surface of the die facing the substrate,wherein the die is interconnected to the substrate via a plurality ofconductive pillar bumps on the active surface, wherein at least one ofthe plurality of conductive pillar bumps has a bump width that issubstantially from equal to or larger than a line width of a trace onthe die attach surface of the substrate to two-and-a-half times smallerthan the line width of a trace on the die attach surface of thesubstrate.

Still another exemplary embodiment of a semiconductor package includes asubstrate. A conductive trace is disposed on the substrate. A conductivepillar bump is disposed on the conductive trace, wherein the conductivebump is coupled to a die.

Yet another exemplary embodiment of a semiconductor package includes asubstrate. A first conductive trace is disposed on the substrate. Asolder resistance layer is disposed on the substrate, having anextending portion covering a portion of the first conductive trace,wherein the extending portion of the solder resistance layer has avertical sidewall extruding over to an adjacent vertical sidewall of theportion of the first conductive trace. A second conductive trace fortransmitting signals is disposed on the substrate. A conductive pillarbump is disposed on the second conductive trace, connecting to aconductive bump or a bond pad of the semiconductor die. A first metalpad is disposed between the second conductive trace and the conductivepillar bump or between the second conductive trace and the substrate. Adie is disposed over the first conductive trace.

A detailed description is given in the following embodiments withreference to the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

The invention can be more fully understood by reading the subsequentdetailed description and examples with references made to theaccompanying drawings, wherein:

FIG. 1 shows a cross section of one exemplary embodiment of asemiconductor package of the invention.

FIG. 2 is a cross section showing the detailed structure of theconductive pillar bump on a die of one exemplary embodiment of asemiconductor package of the invention.

FIG. 3 shows a plane view of a metal pad and the conductive pillar bumpof one exemplary embodiment of a semiconductor package of the invention.

FIG. 4a is a plan view showing a portion of another exemplary embodimentof a semiconductor package of the invention.

FIG. 4b is a partial sectional view taken along line I-I′ in FIG. 4 a.

FIGS. 5a to 5f are plan views showing shapes of various embodiments of aconductive pillar bump of the invention.

FIG. 6a shows a top view of yet another exemplary embodiment of asemiconductor package of the invention.

FIG. 6b shows one possible cross section along line A-A′ of FIG. 6 a.

FIG. 6c shows another possible cross section along line A-A′ of FIG. 6a.

FIGS. 6d, 6e and 6f are enlarged views of portions of FIGS. 6b and 6c ,showing detailed arrangements of the conductive structures.

FIGS. 7a to 7f are plan views showing shapes of various embodiments ofan additional metal pad of the invention.

FIGS. 8a to 8h are top views of various exemplary embodiments of anarrangement between conductive pillar bumps and the correspondingconductive traces of the invention, wherein the conductive traces serveas signal/ground trace segments for routing.

FIGS. 9a to 9h are top views of various exemplary embodiments of anarrangement between conductive pillar bumps and the correspondingconductive traces of the invention, wherein each of the conductivetraces has a terminal portion serving as a pad portion.

DETAILED DESCRIPTION OF INVENTION

The following description is a mode for carrying out the invention. Thisdescription is made for the purpose of illustrating the generalprinciples of the invention and should not be taken in a limiting sense.The scope of the invention is best determined by reference to theappended claims. Wherever possible, the same reference numbers are usedin the drawings and the descriptions to refer the same or like parts.

The present invention will be described with respect to particularembodiments and with reference to certain drawings, but the invention isnot limited thereto and is only limited by the claims. The drawingsdescribed are only schematic and are non-limiting. In the drawings, thesize of some of the elements may be exaggerated and not drawn to scalefor illustrative purposes. The dimensions and the relative dimensions donot correspond to actual dimensions to practice of the invention.

FIG. 1 shows a partial cross section of one exemplary embodiment of asemiconductor package 500 a of the invention. FIG. 2 is a cross sectionshowing the detailed structure of the conductive pillar bump on a die ofone exemplary embodiment of a semiconductor package 500 a of theinvention. In this embodiment, the semiconductor package 500 a is a flipchip package using conductive pillar bumps, for example, copper pillarbumps, connecting a semiconductor die and a substrate. Please refer toFIG. 1 and FIG. 2, the semiconductor package 500 a comprises a substrate200 having a die attach surface 200 a. In one embodiment, the substrate200 may be formed of by semiconductor materials such as silicon, ororganic materials such as bismaleimide triazine, (BT), polyimide orAjinomoto build-up film (ABF). A plurality of conductive traces 210 a,210 b, 220 a and 220 b are disposed on the die attach surface 200 a ofthe substrate 200. In one embodiment, the conductive traces 210 a, 210b, 220 a and 220 b may comprise signal traces or ground traces, whichare used for input/output (I/O) connections of a semiconductor die 210mounted directly onto the substrate 200.

The die attach surface 200 a can be covered with a solder mask 260. Inthis embodiment, the solder mask 260 can be composed of photosensitivematerial and can be patterned by photolithographic methods to partiallyexpose the conductive traces 210 a, 210 b, 220 a and 220 b and a portionof the die attach surface 200 a. For example, the solder mask 260 withina predetermined open area that is directly under the die 300 may beremoved to form an open solder mask or open solder resist configurationsuch that the conductive traces 210 a, 210 b, 220 a and 220 b areexposed within the predetermined open area.

A semiconductor die or die 300 is mounted on the die attach surface 200a of the substrate 200 with the active surface of the die 300 facing thesubstrate 200. The circuitry of the die 300 is interconnected to thecircuitry of the substrate 200 via a novel trace bump trace (TBT)interconnection scheme. The TBT interconnection scheme features aplurality of lathy conductive pillar bumps 230 a and 230 b disposed onthe active surface of the die 300. At least one of the conductive pillarbumps 230 a and 230 b may be composed of a metal stack comprising a UBM(under bump metallurgy) layer such as a sputtered UBM layer (notexplicitly shown), a copper layer 232 such as a plated copper layer 232,and a solder cap 234. The detailed structure of conductive pillar bumps230 a and 230 b will be discussed later.

Referring to FIG. 1, the conductive pillar bumps 230 a and 230 bcorrespond to the conductive traces 210 a and 210 b on the die attachsurface 200 a respectively. During the flip chip assembly, the twoconductive pillar bumps 230 a and 230 b, for example, are bonded ontothe conductive traces 210 a and 210 b, respectively. Due to the smallsize of the conductive pillar bumps 230 a and 230 b, the stress isreduced, the bump-to-trace space is increased and the problem ofbump-to-trace bridging can be effectively avoided. Furthermore, anincreased routing space can be obtained. After the reflowing process, anunderfill material or underfill 204 can be introduced into the gapbetween the die 300 and the substrate 200 with an increased stand-offheight H. The increased stand-off height H facilitates the underfillprocess. According to the embodiment, the underfill 204 may be capillaryunderfill (CUF), molded underfill (MUF) or a combination thereof.

FIG. 2 is a cross section showing the detailed structure of theconductive pillar bump 310 on the one exemplary embodiment of a die 300of the invention. The sectional view of the conductive pillar bump istaken along the lengthwise direction of the conductive pillar bump. Asshown in FIG. 2, the die 300 may include a base 240, a first passivationlayer 242 overlying the base 240, a metal pad 243 overlying the firstpassivation layer 242, a second passivation layer 244 covering the metalpad 243 and the first passivation layer 242, and a stress bufferinglayer 246 overlying the second passivation layer 244. The term“overlying” can mean, but is not limited to, “on” or “over”. In thisembodiment, the base 240 may include but is not limited to asemiconductor substrate, circuit elements fabricated on the main surfaceof the semiconductor substrate, inter-layer dielectric (ILD) layers andinterconnection structure. In one embodiment, the interconnectionstructure may comprise a plurality of metal layers, a plurality ofdielectric layers alternatively laminated with the metal layers and aplurality of vias formed through the dielectric layers on thesemiconductor substrate. The metal pad 243 belongs to the topmost metallayer of the metal layers of the interconnection structure. Also, thefirst passivation layer 242 belongs to the topmost dielectric layer ofthe dielectric layers of the interconnection structure. The firstpassivation layer 242 may comprise but is not limited to siliconnitride, silicon oxide, silicon oxynitride or any combination thereof.The second passivation layer 244 may comprise but is not limited tosilicon nitride, silicon oxide, silicon oxynitride or any combinationthereof. The stress buffering layer 246 may comprise but is not limitedto polyimide, polybenzoxazole (PBO) or a combination thereof. The metalpad 243 may comprise but is not limited to aluminum, copper or alloysthereof. The stress buffering layer 246 may include the secondpassivation layer 244.

An opening 246 a can be formed in the stress buffering layer 246 toexpose at least a portion of the metal pad 243. The opening 246 a can beany shape. According to the embodiment, the opening 246 may be a lathy,oval-shaped opening elongating along the lengthwise direction of theconductive pillar bump. A UBM layer 231 can be formed on the exposedmetal pad 243 within the opening 246 a. The UBM layer 231 may alsoextend onto a top surface of the stress buffering layer 246. In thisembodiment, the UBM layer 231 may be formed by sputtering methods andmay comprise titanium, copper or a combination thereof. A copper layer232 such as an electroplated copper layer can be formed on the UBM layer231. The opening 326 can be filled with the copper layer 232 and the UBMlayer 231, and the copper layer 232 and the UBM layer 231 within theopening 246 may form an integral plug 232 a that electrically couplesthe conductive pillar bump 230 with the underlying metal pad 243. Asolder cap 234 can be formed on the copper layer 232. A nickel layer 233may be formed between the copper layer 232 and the solder cap 234. Thecopper layer, such as copper layer 232, may be a part of are-distribution layer (RDL) or may be fabricated concurrently with theRDL.

FIG. 3 shows a plane view of a metal pad 243 and the conductive pillarbump 310 of one exemplary embodiment of a semiconductor package of theinvention. In this embodiment, to improve routing ability forhigh-density semiconductor packages, a size of the metal pad can beshrunk with a shape similar to the corresponding conductive pillar bumpin a plane view. In one embodiment, the metal pad may have 2-foldrotational symmetry only in a plane view, for example, the metal pad maybe an octangular shape or oval-shape. In one embodiment as shown in FIG.3, the metal pad 243 formed on the die attach surface of the substratemay be an octangular shape. The metal pad 243 has a first edge 243 aalong a first direction 270 and a second edge 243 b along a seconddirection 272, wherein the second edge 243 b is substantially verticalto the first edge 243 a. Also, the first edge 243 a is not adjacent tothe second edge 243 b. In this embodiment, the first edge 243 a alongthe first direction 270 can be designed differently from that of thesecond edge 243 b along the second direction 272 in the plan view. Also,a first length L1 of the metal pad 243 along the first direction 270 canbe designed differently from a second length L2 of the metal pad 243along the second direction 272 in the plan view as shown in FIG. 3. Inthis embodiment, a ratio of the first length L1 to the second length L2can be designed between about 46:45 and 99:54. In one embodiment, anangle a between the first direction 270 and the second direction 272 maybe designed larger than 0 degrees and less than or equal to 90 degrees.

In another embodiment of a semiconductor package which the metal pad 243is an oval-shape or another 180-degree rotationally symmetrical shape, afirst length L1 of the metal pad 243 along the first direction 270 canbe designed differently from a second length L2 of the metal pad 243along the second direction 272 in the plan view. Also, a ratio of thefirst length L1 to the second length L2 can be designed between about46:45 and 99:54. Further, an angle a between the first direction 270 andthe second direction 272 may be designed larger than 0 degrees and lessthan or equal to 90 degrees. For example, if the metal pad 243 is anoval-shape, the first direction 270 is also along a major axis of themetal pad 243, and the second direction 272 is also along a minor axisof the metal pad 243.

As shown in FIGS. 2 and 3, the opening 246 a formed in the stressbuffering layer 246 to expose at least a portion of the metal pad 243.In this embodiment as shown in FIG. 3, the opening 246 a is anoctangular shape in the plan view. Also, the opening 246 a has a thirdlength L3 along the first direction 270 and a fourth length L4 differentfrom the third length L3 along the second direction 272 in the planview. In another embodiment, the opening 246 a may be an oval-shape oranother 180-degree rotationally symmetrical shape, like the metal pad243. Additionally, the conductive pillar bump 310 may be an octangularshape or oval shape in the plan view.

Alternatively, a width or length ratio of the conductive pillar bump tothe conductive trace can be designed for further improvement of routingability for high-density semiconductor packages. FIG. 4a is a plan viewshowing a portion of another exemplary embodiment of a semiconductorpackage 500 b of the invention. FIG. 4b is a partial sectional viewtaken along line I-I′ in FIG. 4a . In this embodiment, the semiconductorpackage 500 b is a flip chip package using conductive pillar bumps, forexample, copper pillar bumps, connecting a semiconductor die and asubstrate. Elements of the embodiments that are the same or similar asthose previously described with reference to FIGS. 1-3, are hereinafternot repeated for brevity.

In this embodiment, as shown in FIGS. 4a and 4b , at least one of theconductive pillar bumps 230 a and 230 b, when viewed from above, mayhave a rounded and slightly elongated outline extending along theconductive traces 210 a and 210 b. In this embodiment, the bump width Wbof at least one of the conductive pillar bumps, for example, theconductive pillar bump 230 b, is substantially from equal to or largerthan a line width W of the conductive trace, such as the conductivetrace 210 b on the die attach surface 200 a of the substrate 200 totwo-and-a-half times smaller than the line width W of the conductivetrace, such as the conductive trace 210 b on the die attach surface 200a of the substrate 200. In one embodiment, the bump length Lb of atleast one of the conductive pillar bumps, for example, the conductivepillar bump 230 b, may be from two times smaller than the line width ofthe trace to three times greater than the line width W of the conductivetrace, such as the conductive trace 210 b on the die attach surface 200a of the substrate 200. Also, the die 300 may have a bump pitch Pbetween 50 μm and 200 μm.

Additionally, at least one of a plurality of conductive pillar bumps maybe designed as arbitrary shapes except an oval shape to broaden designchoices. For example, at least one of the plurality of conductive pillarbumps may be a non-round or asymmetric shape from the plan view. FIGS.5a to 5f are plan views showing shapes of various embodiments of aconductive pillar bump. As shown in FIGS. 5a to 5f , the conductivepillar bumps 230 a 1-230 a 6 are exemplary embodiments of non-round orasymmetric shaped conductive pillar bumps, it is to be understood thatthe invention is not limited to the disclosed embodiments.

FIG. 6a shows a top view of yet another exemplary embodiment of asemiconductor package 500 c of the invention. FIG. 6b shows one possiblecross section along line A-A′ of FIG. 6a . FIG. 6c shows anotherpossible cross section along line A-A′ of FIG. 6a . Yet anotherexemplary embodiment of a semiconductor package 500 c is a flip chippackage using conductive pillar bumps, for example, copper pillar bumps,connecting a semiconductor die and a substrate. As shown in FIGS. 6a to6c , yet another exemplary embodiment of a semiconductor package 500 ccomprises a substrate 600 with first conductive traces 602 and secondconductive traces 604 disposed thereon. In one embodiment, the substrate600 may be formed of semiconductor materials such as silicon, or organicmaterials such as bismaleimide triazine, (BT), polyimide or Ajinomotobuild-up film (ABF). In one embodiment, the first conductive trace 602and the second conductive trace 604 may comprise signal traces or groundtraces, which are used for input/output (I/O) connections of asemiconductor die 610 mounted directly onto the substrate 600. In thisembodiment each of the first conductive traces 602 has a portion 602 aas a pad region of the substrate 600, and each of the second conductivetraces 604 serves as a signal/ground trace segment for routing.

Still referring to FIGS. 6a to 6c , a solder resistance layer 606 isformed covering the substrate 600. Also, the solder resistance layer606, except for extending portions 608, exposes an overlapping regionbetween a subsequently mounted semiconductor die 610 and the substrate600. It is noted that the extending portions 608 of the solderresistance layer 606 extends along the second conductive trace 604 andcovers a portion of the second conductive trace 604. Also, the solderresistance layer 606, except for extending portions 608, is disposedaway from the subsequently mounted semiconductor die 610 by a distanced1. In one embodiment, the solder resistance layer 606 may comprisesolder mask materials, oxide, nitride, or oxynitride. As shown in FIG.6b , the extending portions 608 of the solder resistance layer 606covers a portion 604 a of the second conductive trace 604. It is notedthat a width W2 of the extending portion 608 of the solder resistancelayer 606 is designed to be larger than a width W1 of the portion 604 aof the second conductive trace 604, so that a portion of a bottomsurface 609 of the extending portion 608 of the solder resistance layer606 is exposed from the portion 604 a of the second conductive trace604, and the extending portion 608 of the solder resistance layer 606has a vertical sidewall 607 extruding over to an adjacent verticalsidewall 605 of the portion 604 a of the second conductive trace 604.Therefore, the extending portion 608 and the portion 604 a of the firstconductive trace 204 collectively have a T-shaped cross section.

Still referring to FIGS. 6a to 6c , conductive pillar bumps 616 are thenformed over the portions (pad regions) 602 a of the first conductivetraces 602. In this embodiment, each of the conductive pillar bumps 616is composed by a metal stack comprising a UBM (under bump metallurgy)layer (not explicitly shown), a copper layer 614, and a solder cap 612.Alternatively, conductive buffer layers (not shown) formed of Ni may beformed between the conductive pillar bumps 616 and the portions (padregions) 602 a of the first conductive traces 602, and the conductivebuffer layers may serve as seed layers, adhesion layers and barrierlayers for the conductive pillar bumps 616 formed thereon. In oneembodiment, the conductive pillar bumps 616 are used as a solder jointfor a subsequently formed conductive bump or bond pad, which transmitsinput/output (I/O), ground or power signals of the semiconductor die 610formed thereon. Therefore, the conductive pillar bumps 616 may help toincrease the mechanical strength of the bump structure.

Still referring to FIGS. 6a to 6c , the semiconductor die 610 has aplurality of conductive bumps or a bond pads (not shown) disposed on anactive surface 624 thereof mounted on a die attach surface of thesubstrate 600. The metal pads of the semiconductor die 610 respectivelyconnect to the portions (pad regions) 602 a of the first conductivetraces 602 through the conductive pillar bumps 616 therebetween. Asshown in FIG. 6a , the solder resistance layer 606 is disposed away fromthe portions (pad regions) 602 a of the first conductive traces 602,which overlap with the conductive pillar bumps 616, by at least adistance d2. Also, the extending portion 608 of the solder resistancelayer 606 is below the semiconductor die 610, over the active surface624 of the semiconductor die 610 and within a projection area (notshown) of the semiconductor die 610.

Still referring to FIGS. 6a to 6c , an underfill material 620 may fill agap between the substrate 600 and the semiconductor die 610 and coverthe solder resistance layer 606 to compensate for differing coefficientsof thermal expansion (CTE) between the substrate, the conductive tracesand the semiconductor die. In this embodiment, the portion of the bottomsurface 609 of the extending portion 608 of the solder resistance layer606 is wrapped by the underfill material 620.

The underfill material wraps the portion of the bottom surface of theextending portion of the solder resistance layer, which has a widerwidth than the portion of the first conductive trace, so that theunderfill material may be anchored with a T-shaped feature formed byboth the extending portion of the solder resistance layer and theportion of the first conductive trace. Thus, the conventional underfilldelamination problem occurring between the conductive trace and theunderfill material is improved. Also, the extending portion of thesolder resistance layer only extends into a projection area of the dieto cover a portion of the first conductive trace, and the remainingportion of the solder resistance layer is disposed away from thesemiconductor die by a distance, so that the semiconductor package stillhas enough space to allow the underfill material to flow to fill the gapbetween the substrate and the semiconductor die. Therefore, theextending portion of the solder resistance layer does not affect theperformance of the dispensing process. Moreover, exemplary embodimentsof a semiconductor package can be used in many types of package methods.For example, a gap between the substrate and the semiconductor die canbe filled with a molding compound only. Alternatively, the gap betweenthe substrate and the semiconductor die can be filled with a moldingcompound and an underfill material. Further, the gap between thesubstrate and the semiconductor die can be filled with an underfillmaterial only.

Additionally, an additional conductive structure may be added under orabove the first conductive trace 602 comprising signal traces or groundtraces to broaden design choices. A position of the additionalconductive structure may be designed overlapping the conductive pillarbump or away from the conductive pillar bump. As shown in FIGS. 6a to 6c, a conductive structure 620 a, 620 b, 620 c or 620 d may be disposedbetween the first conductive trace 602 and the conductive pillar bump616 or between the first conductive trace 602 and the substrate 600. Inone embodiment as shown in FIGS. 6a and 6b , a conductive structure 620a 1 or 620 c 1 is disposed between the first conductive trace 602 andthe substrate 600. Also, the conductive structure 620 a 1 or 620 c 1contacts the first conductive trace 602 and the substrate 600,overlapping with the conductive pillar bump 616. Further, a conductivestructure 620 b 1 or 620 d 1 is disposed overlapping a portion of thefirst conductive trace 602 and the semiconductor die 610, wherein theportion of the first conductive trace 602 is away from the conductivepillar bump 616. In another embodiment as shown in FIGS. 6a and 6c , aconductive structure 620 a 2 or 620 c 2 is disposed between the firstconductive trace 602 and the conductive pillar bump 616. Also, theconductive structure 620 a 2 or 620 c 2 contacts the first conductivetrace 602 and the conductive pillar bump 616, overlapping with theconductive pillar bump 616. Further, a conductive structure 620 b 2 or620 d 2 is disposed overlapping a portion of the first conductive trace602 and the substrate 600, wherein the portion of the first conductivetrace 602 is away from the conductive pillar bump 616.

In one embodiment, the conductive structure 620 a, 620 b, 620 c or 620 dmay be used for transmitting signals. In one embodiment, the conductivestructure 620 a, 620 b, 620 c or 620 d may comprise a single-layerstructure. In this embodiment, the conductive structures 620 a and 620 bare single-layer structures, and the conductive structures 620 c and 620d are multi-layer structures. In one embodiment, the single-layerstructure may comprise a conductive trace or a metal pad. In oneembodiment, the multi-layer structure is a stack of conductive traces,metal pads or combinations thereof. In one embodiment as shown in FIGS.6b and 6c , the conductive structures 620 c 1/620 c 2 disposed betweenthe first conductive trace 602 and the substrate 600 may compriseconductive structure portions 620 c 1-1/620 c 2-1, 620 c 1-2/620 c 2-2and 620 c 1-3/620 c 2-3, from top to bottom. Each of the conductivestructure portions 620 c 1-1/620 c 2-1, 620 c 1-2/620 c 2-2 and 620 c1-3/620 c 2-3 may comprise a conductive trace or a metal pad. Forexample, the conductive structure portions 620 c 1-1/620 c 2-1, 620 c1-2/620 c 2-2 and 620 c 1-3/620 c 2-3 may be a conductive trace, a metalpad and another conductive trace, respectively. Therefore, theconductive structure portions 620 c 1-1/620 c 2-1, 620 c 1-2/620 c 2-2and 620 c 1-3/620 c 2-3 may collectively compose a stack of conductivetraces, metal pads or combinations thereof. However, it should be notedthat there is no limitation on the number of the conductive structureportions.

Similarly, in one embodiment as shown in FIGS. 6b and 6c , theconductive structure 620 d 1/620 d 2 disposed overlapping a portion ofthe first conductive trace 602 and the semiconductor die 610 maycomprise conductive structure portions 620 d 1-1/620 d 2-1, 620 d1-2/620 d 2-2 and 620 d 1-3/620 d 2-3, from top to bottom. Each of theconductive structure portions 620 d 1-1/620 d 2-1, 620 d 1-2/620 d 2-2and 620 d 1-31620 d 2-3 may comprise a conductive trace or a metal pad.For example, the conductive structure portions 620 d 1-1/620 d 2-1, 620d 1-2/620 d 2-2 and 620 d 1-3/620 d 2-3 may be a conductive trace, ametal pad and another conductive trace, respectively. Therefore, theconductive structure portions 620 d 1-1/620 d 2-1, 620 d 1-2/620 d 2-2and 620 d 1-3/620 d 2-3 may collectively compose a stack of conductivetraces, conductive pads or combinations thereof. However, it should benoted that there is no limitation on the number of the conductivestructure portions.

FIGS. 6d, 6e and 6f are enlarged views of portions of FIGS. 6b and 6c ,showing detailed arrangements of one exemplary embodiment of theconductive structures 620 a 1, 620 a 2, 620 b 2, 620 c 1 and 620 d 2.FIG. 6d illustrates a detailed arrangement of the conductive structure620 a 1 or 620 b 2 as shown in FIGS. 6b and 6c . In this embodiment, theconductive structure 620 a 1/620 b 2, which serves as a metal pad 620 a1/620 b 2, is directly disposed on the substrate 600 and the firstconductive trace 602 is disposed on top of the metal pad 620 a 1/620 b2.

FIG. 6e illustrates a detailed arrangement of one exemplary embodimentof the conductive structure 620 a 2 as shown in FIG. 6c . In thisembodiment, the first conductive trace 602 is disposed on the substrate600. Also, the conductive structure 620 a 2, which serves as a metal pad620 a 2, is disposed on the first conductive trace 602. Further, theconductive pillar bump 616 is disposed on top of the metal pad 620 a 2.

FIG. 6f illustrates a detailed arrangement of one exemplary embodimentof the conductive structure 620 c 1 or 620 d 2 as shown in FIGS. 6b and6c . In this embodiment, the conductive structure 620 c 1/620 d 2 isdirectly disposed on the substrate 600 and a conductive trace (e.g. thefirst conductive trace 602 as shown in FIGS. 6b and 6c ) or a conductivepillar bump (e.g. the conductive pillar bump 616 as shown in FIGS. 6band 6c ) is disposed on top of the conductive structure 620 c 1/620 d 2.In this embodiment, the conductive structure 620 c 1/620 d 2 maycomprise conductive structure portions 620 c 1-1/620 d 2-1, 620 c1-2/620 d 2-2 and 620 c 1-3/620 d 2-3, from top to bottom. In thisembodiment, the conductive structure portions 620 c 1-1/620 d 2-1, 620 c1-2/620 d 2-2 and 620 c 1-3/620 d 2-3 may serve a conductive trace 620 c1-1/620 d 2-1, a metal pad 620 c 1-2/620 d 2-2 and another conductivetrace 620 c 1-3/620 d 2-3, respectively. FIG. 6f shows the metal pad 620c 1-2/620 d 2-2 is sandwiched by a multi-layer trace structure composedby the conductive trace 620 c 1-1/620 d 2-1 and the conductive trace 620c 1-3/620 d 2-3. In one embodiment, the metal pad 620 c 1-2/620 d 2-2may be replaced by a more conductive metal pad.

The additional conductive structure added under or above the firstconductive trace 602 may have various shapes in the plan view for designchoices. FIGS. 7a to 7f are plan views showing shapes of variousembodiments of an additional conductive structure of the invention. Asshown in FIGS. 7a to 7f , the conductive structures 720 a 1-720 a 6 areexemplary embodiments of polygonal-shaped, rounded-shaped, ordrop-shaped conductive structures. For example, the conductive structure720 a 1 as shown in FIG. 7a is a rectangular shape, the conductivestructure 720 a 2 as shown in FIG. 7b is a square shape, the conductivestructure 720 a 3 as shown in FIG. 7c is a crescent shape, theconductive structure 720 a 4 as shown in FIG. 7d is a decagonal shape,the conductive structure 720 a 5 as shown in FIG. 7e is a trapezoidalshape, and the conductive structure 720 a 6 as shown in FIG. 7e is adrop-shape. It is to be understood that the invention is not limited tothe disclosed embodiments.

Moreover, the conductive pillar bump disposed on the semiconductor dieand the corresponding conductive traces disposed on the substrate mayhave various arrangements to broaden design choices. FIGS. 8a to 8h aretop views of various exemplary embodiments of an arrangement betweenconductive pillar bumps 816 and the corresponding conductive traces 804a-804 h of the invention. In this embodiment, the conductive traces 804a-804 h may comprise signal traces or ground traces, which are used forinput/output (I/O) connections of a semiconductor die (e.g. thesemiconductor die 610 as shown in FIG. 6a ) mounted directly onto thesubstrate (e.g. the substrate 600 as shown in FIG. 6a ). In thisembodiment, each of the conductive traces 804 a-804 h serves as asignal/ground trace segment for routing.

As shown in FIG. 8a , the conductive trace 804 a has at least a firstportion 101 having a first width 103 and a second portion 102 having asecond width 104. A conductive pillar bump 816 is disposed on the secondportion 102 of the conductive trace. In this embodiment, the secondwidth 104 of the second portion 102 is designed larger than the firstwidth 103 of the first portion 101. Also, the second width 104 of thesecond portion 102 of the conductive trace 804 a for the conductivepillar bump 816 bonded thereon is designed larger than a width of theconductive pillar bump 816. Further, profiles of opposite edges of thesecond portion 102 of the conductive trace 804 a may be designed similarto a profile of the conductive pillar bump 816 in a top view. Therefore,the conductive pillar bump 816 is disposed within the second portion 102of the conductive trace 804 a in the top view.

As shown in FIG. 8b , the conductive trace 804 b has a uniform width,and a plurality of (such as three) conductive pillar bumps 816 areformed closely to each other. In this embodiment, the conductive pillarbumps 816 having a smaller width are collectively used to replace asingle conductive pillar bump with a larger width. For example, a widthof the conductive pillar bumps 816 as shown in FIG. 8b is designedsmaller than a width of the conductive pillar bumps 816 as shown in FIG.8 a.

As shown in FIG. 8c , the conductive trace 804 c has at least a firstportion 101 having a first width 103 and a second portion 102 having asecond width 104. A conductive pillar bump 816 is disposed on the secondportion 102 of the conductive trace 804 c. In this embodiment, thesecond width 104 of the second portion 102 is designed larger than thefirst width 103 of the first portion 101 of the conductive trace 804 c.Also, the second width 104 of the second portion 102 of the conductivetrace 804 c for the conductive pillar bump 816 bonded thereon isdesigned larger than a width of the conductive pillar bump 816. In thisembodiment, a profile of only one side of opposite edges of the secondportion 102 of the conductive trace 804 c is designed similar to aprofile of the conductive pillar bump 816 in a top view. Therefore, theconductive pillar bump 816 is disposed within the second portion 102 ofthe conductive trace 804 c in the top view.

As shown in FIG. 8d , a second portion 102 of the conductive trace 804 chas second width 104 much larger than a first width 103 of a firstportion 101 of the conductive trace 804 c to provide a plurality ofconductive pillar bumps 816 disposed thereon. In this embodiment, edgesof the second portion 102 of the conductive trace 804 d may be designedsurrounding all of the conductive pillar bumps 816 in a top view.Therefore, the conductive pillar bumps 816 are disposed within thesecond portion 102 of the conductive trace 804 d in the top view.

As shown in FIG. 8e , a second portion 102 of the conductive trace 804 ehas second width 104 much larger than a first width 103 of a firstportion 101 of the conductive trace 804 e to provide a conductive pillarbump 816 disposed thereon. In this embodiment, the second portion 102 ofthe conductive trace 804 e may be design having a uniform width (thesecond width 104). Also, opposite edges of the second portion 102 of theconductive trace 804 e may be parallel to each other in a top view.

As shown in FIG. 8f , the conductive trace 804 f has at least a firstportion 101 having a first width 103, a least a second portion 102having a second width 104 and a least a third portion 105 having a thirdwidth 106. In this embodiment, the single second portion 102 may bedesigned between two of the first portions 101 of the conductive trace804 f. Also, the single third portion 105 may be designed between two ofthe first portions 101 of the conductive trace 804 f. In thisembodiment, the second width 104 of the second portion 102 and the thirdwidth 106 of the third portion 105 are designed larger than the firstwidth 103 of the first portion 101 of the conductive trace 804 f. Also,the second width 104 of the second portion 102 and the third width 106of the third portion 105 of the conductive trace 804 f are designedlarger than a width of the conductive pillar bump 816. It is noted thatthe second portion 102 of the conductive trace 804 f is designed for theconductive pillar bump 816 bonded thereon. Also, the third portion 105of the conductive trace 804 f is formed but no conductive pillar bump isformed thereon. Further, the second portion 102 of the conductive trace804 f may be designed to have a profile similar to the second portion102 of the conductive trace 804 a or 804 c as shown in FIG. 8a or 8 c.

FIG. 8g and FIG. 8h illustrate the relationship between a bump width Bof the conductive pillar bump 816 and a trace width W of the conductivetrace 804 g/804 h. In one embodiment, the trace width W of theconductive trace 804 g may be designed small than the bump width B ofthe conductive pillar bump 816. In another embodiment, the trace width Wof the conductive trace 804 h may be designed larger than the bump widthB of the conductive pillar bump 816. In one embodiment, the relationshipbetween a bump width B of the conductive pillar bump 816 and a tracewidth W of the conductive trace 804 g/804 h may be 10W<B<W/10.

FIGS. 9a to 9h are top views of various exemplary embodiments of anarrangement between conductive pillar bumps 816 and the correspondingconductive traces 804 a-804 h of the invention. In this embodiment, theconductive traces 902 a-902 h may comprise signal traces or groundtraces, which are used for input/output (I/O) connections of asemiconductor die (e.g. the semiconductor die 610 as shown in FIG. 6a )mounted directly onto the substrate (e.g. the substrate 600 as shown inFIG. 6a ). In this embodiment, each of the conductive traces 904 a-904 hhas a portion as a pad portion of the substrate.

As shown in FIG. 9a , the conductive trace 902 a has a first portion 101having a first width 103 and a second portion 102 having a second width104. In this embodiment, the second portion 102 of the conductive trace902 a serving as a pad portion 102. A conductive pillar bump 916 isdisposed on the second portion 102 of the conductive trace. In thisembodiment, the second width 104 of the second portion 102 is designedlarger than the first width 103 of the first portion 101 of theconductive trace 902 a. Also, the second width 104 of the second portion102 of the conductive trace 902 a for the conductive pillar bump 916bonded thereon is designed larger than a width of the conductive pillarbump 916. Further, a profile of the second portion 102 of the conductivetrace 902 a may be designed similar to a profile of the conductivepillar bump 916 in a top view. Therefore, the conductive pillar bump 816is disposed within the second portion 102 of the conductive trace 902 ain the top view.

As shown in FIG. 9b , the conductive trace 902 b has a uniform width,and a plurality of (such as three) conductive pillar bumps 916 areformed closely to each other. In this embodiment, the second portion 102of the conductive trace 902 b serving as a pad portion 102. In thisembodiment, the conductive pillar bumps 916 having a smaller width arecollectively used to replace a single conductive pillar bump with alarger width. For example, a width of the conductive pillar bumps 916 asshown in FIG. 9b is designed smaller than a width of the conductivepillar bumps 916 as shown in FIG. 9 a.

As shown in FIG. 9c , the conductive trace 902 c has a first portion 101having a first width 103 and a second portion 102 having a second width104. In this embodiment, the second portion 102 of the conductive trace902 c serving as a pad portion 102. A conductive pillar bump 916 isdisposed on the second portion 102 of the conductive trace 902 c. Inthis embodiment, the second width 104 of the second portion 102 isdesigned larger than the first width 103 of the first portion 101 of theconductive trace 902 c. Also, the second width 104 of the second portion102 of the conductive trace 902 c for the conductive pillar bump 916bonded thereon is designed larger than a width of the conductive pillarbump 916. In this embodiment, a profile of only one side of oppositeedges of the second portion 102 of the conductive trace 902 c isdesigned similar to a profile of the conductive pillar bump 916 in a topview. Therefore, the conductive pillar bump 916 is disposed within thesecond portion 102 of the conductive trace 902 c in the top view.

As shown in FIG. 9d , a second portion 102 of the conductive trace 902 chas second width 104 much larger than a first width 103 of a firstportion 101 of the conductive trace 902 c to provide a plurality ofconductive pillar bumps 916 disposed thereon. In this embodiment, thesecond portion 102 of the conductive trace 902 d serving as a padportion 102. In this embodiment, edges of the second portion 102 of theconductive trace 902 d may be designed surrounding all of the conductivepillar bumps 916 in a top view. Therefore, the conductive pillar bumps916 are disposed within the second portion 102 of the conductive trace902 d in the top view.

As shown in FIG. 9e , a second portion 102 of the conductive trace 902 ehas second width 104 much larger than a first width 103 of a firstportion 101 of the conductive trace 902 e to provide a conductive pillarbump 916 disposed thereon. In this embodiment, the second portion 102 ofthe conductive trace 902 e serving as a pad portion 102. In thisembodiment, the second portion 102 of the conductive trace 902 e may bedesign having a uniform width (the second width 104). Also, oppositeedges of the second portion 102 of the conductive trace 902 e may beparallel to each other in a top view.

As shown in FIG. 9f , the conductive trace 902 f has at least a firstportion 101 having a first width 103, a least a second portion 102having a second width 104 and a least a third portion 105 having a thirdwidth 106. In this embodiment, the right-most second portion 102 of theconductive trace 902 f serving as a pad portion 102. In this embodiment,the single second portion 102 may be designed between two of the firstportions 101 of the conductive trace 902 f. Also, the single thirdportion 105 may be designed between two of the first portions 101 of theconductive trace 902 f. In this embodiment, the second width 104 of thesecond portion 102 and the third width 106 of the third portion 105 aredesigned larger than the first width 103 of the first portion 101 of theconductive trace 902 f. Also, the second width 104 of the second portion102 and the third width 106 of the third portion 105 of the conductivetrace 902 f are designed larger than a width of the conductive pillarbump 816. It is noted that the second portion 102 of the conductivetrace 902 f is designed for the conductive pillar bump 916 bondedthereon. Also, the third portion 105 of the conductive trace 902 f isformed but no conductive pillar bump is formed thereon. Further, thesecond portion 102 of the conductive trace 902 f may be designed to havea profile similar to the second portion 102 of the conductive trace 902a or 902 c as shown in FIG. 9a or 9 c.

FIG. 9g and FIG. 9h illustrate the relationship between a bump width Bof the conductive pillar bump 916 and a trace width W of the conductivetrace 902 g/902 h. In this embodiment, the conductive trace 902 g/902 hhas a terminal portion serving as a pad portion of the conductive trace902 g/902 h. In one embodiment, the trace width W of the conductivetrace 902 g may be designed small than the bump width B of theconductive pillar bump 916. In another embodiment, the trace width W ofthe conductive trace 902 h may be designed larger than the bump width Bof the conductive pillar bump 916. In one embodiment, the relationshipbetween a bump width B of the conductive pillar bump 916 and a tracewidth W of the conductive trace 902 g/902 h may be 10W<B<W/10.

While the invention has been described by way of example and in terms ofthe preferred embodiments, it is to be understood that the invention isnot limited to the disclosed embodiments. On the contrary, it isintended to cover various modifications and similar arrangements (aswould be apparent to those skilled in the art). Therefore, the scope ofthe appended claims should be accorded the broadest interpretation so asto encompass all such modifications and similar arrangements.

What is claimed is:
 1. A semiconductor package, comprising: a substratehaving a die attach surface; a conductive trace disposed on thesubstrate, wherein the conductive trace is elongated and carries asignal or a ground across at least a portion of the substrate; aconductive structure disposed on the conductive trace at an intermediateportion thereof; and a die mounted on the die attach surface of thesubstrate via a conductive pillar bump, the conductive pillar bump beingrounded and elongated such that the conductive pillar bump extends alonga length of the conductive trace and contacts the conductive trace at anend thereof; wherein the die comprises a metal pad electrically couplingto the conductive pillar bump, wherein the metal pad has a first edgeand a second edge substantially vertical to the first edge, wherein alength of the first edge is different from that of the second edge froma plan view, and wherein the first edge is not adjacent to the secondedge.
 2. The semiconductor package as claimed in claim 1, furthercomprising an underfill between the die and the substrate, and whereinthe die further comprises: an interconnection structure between asemiconductor substrate and the conductive pillar bump, wherein theinterconnection structure comprises a plurality of metal layers and aplurality of dielectric layers, wherein the interconnection structurecomprises a first passivation layer formed by an uppermost dielectriclayer of the dielectric layers of the interconnection structure; and asecond passivation layer disposed between the semiconductor substrateand the conductive pillar bump, on the metal pad.
 3. The semiconductorpackage as claimed in claim 1, wherein the metal pad is an octangularshape in the plan view.
 4. The semiconductor package as claimed in claim2, wherein the metal pad is formed by a topmost metal layer of the metallayers of the interconnection structure.
 5. The semiconductor package asclaimed in claim 1, wherein the conductive pillar bump is composed of ametal stack comprising an under bump metallurgy (UBM) layer, a copperlayer, and a solder cap.
 6. The semiconductor package as claimed inclaim 1, wherein the metal pad has a similar shape to the correspondingconductive pillar bump in the plan view.
 7. The semiconductor package asclaimed in claim 2, wherein the second passivation layer has an openingtherein to expose the metal pad.
 8. The semiconductor package as claimedin claim 7, wherein the opening is an octangular shape in the plan viewand the opening has a third edge and a fourth edge substantiallyvertical to each other, wherein a length of the third edge is differentfrom a length of the fourth edge in the plan view.
 9. A semiconductorpackage, comprising: a substrate having a die attach surface; aconductive trace disposed on the substrate, wherein the conductive traceis elongated and carries a signal or a ground across at least a portionof the substrate; a conductive structure disposed on the conductivetrace at an intermediate portion thereof; and a die mounted on the dieattach surface of the substrate via a conductive pillar bump, theconductive pillar bump being rounded and elongated such that theconductive pillar bump extends along a length of the conductive traceand contacts the conductive trace at an end thereof; wherein the diecomprises a metal pad electrically coupling to the conductive pillarbump, wherein the metal pad is an octangular shape in plan view and hasa first length along a first direction and a second length, which isdifferent from the first length, along a second direction from the planview, wherein an angle between the first direction and the seconddirection is equal to 90 degrees.
 10. The semiconductor package asclaimed in claim 9, further comprising an underfill between the die andthe substrate, and wherein the die further comprises: an interconnectionstructure between a semiconductor substrate and the conductive pillarbump, wherein the interconnection structure comprises a plurality ofmetal layers and a plurality of dielectric layers, wherein theinterconnection structure comprises a first passivation layer formed byan uppermost dielectric layer of the dielectric layers of theinterconnection structure; and a second passivation layer disposedbetween the semiconductor substrate and the conductive pillar bump, onthe metal pad.
 11. The semiconductor package as claimed in claim 10,wherein the metal pad is formed by a topmost metal layer of the metallayers of the interconnection structure.
 12. The semiconductor packageas claimed in claim 9, wherein the conductive pillar bump is composed ofa metal stack comprising an under bump metallurgy (UBM) layer, a copperlayer, and a solder cap.
 13. The semiconductor package as claimed inclaim 9, wherein the metal pad has similar shape to the correspondingconductive pillar bump in the plan view.
 14. The semiconductor packageas claimed in claim 10, wherein the second passivation layer has anopening therein to expose the metal pad.
 15. The semiconductor packageas claimed in claim 14, wherein the opening is an octangular shape inthe plan view and the opening has a third length along the firstdirection and a fourth length, which is different from the third length,along the second direction in the plan view.
 16. The semiconductorpackage as claimed in claim 9, wherein a ratio of the first length tothe second length is between 46:45 and 99:54.
 17. A semiconductorpackage, comprising: a substrate having a die attach surface; aconductive trace disposed on the substrate, wherein the conductive traceis elongated and carries a signal or a ground across at least a portionof the substrate; a conductive structure disposed on the conductivetrace at an intermediate portion thereof; and a die mounted on the dieattach surface of the substrate via a conductive pillar bump, theconductive pillar bump being rounded and elongated such that theconductive pillar bump extends along a length of the conductive traceand contacts the conductive trace at an end thereof; wherein the diecomprises a metal pad electrically coupling to the conductive pillarbump, wherein the metal pad has 2-fold rotational symmetry, which is a180 degrees rotation around a middle point of the metal pad, only from aplan view, wherein the metal pad has a first edge and a second edgesubstantially vertical to the first edge, wherein a length of the firstedge is different from that of the second edge from the plan view, andwherein the first edge is not adjacent to the second edge.
 18. Thesemiconductor package as claimed in claim 17, wherein the metal pad hasa first length along a first direction and a second length, which isdifferent from the first length, along a second direction from a planview, wherein an angle between the first direction and the seconddirection is larger than 0 degrees and less than or equal to 90 degrees.19. The semiconductor package as claimed in claim 17, further comprisingan underfill between the die and the substrate, and wherein the diefurther comprises: an interconnection structure between a semiconductorsubstrate and the conductive pillar bump, wherein the interconnectionstructure comprises a plurality of metal layers and a plurality ofdielectric layers, wherein the interconnection structure comprises afirst passivation layer formed by an uppermost dielectric layer of thedielectric layers of the interconnection structure; and a secondpassivation layer disposed between the semiconductor substrate and theconductive pillar bump, on the metal pad.
 20. The semiconductor packageas claimed in claim 17, wherein the metal pad is an octangular shape inthe plan view.
 21. The semiconductor package as claimed in claim 19,wherein the metal pad is formed by a topmost metal layer of the metallayers of the interconnection structure.
 22. The semiconductor packageas claimed in claim 17, wherein the conductive pillar bump is composedof a metal stack comprising an under bump metallurgy (UBM) layer, acopper layer, and a solder cap.
 23. The semiconductor package as claimedin claim 17, wherein the metal pad has similar shape to thecorresponding conductive pillar bump in the plan view.
 24. Thesemiconductor package as claimed in claim 19, wherein the secondpassivation layer has an opening therein to expose the metal pad. 25.The semiconductor package as claimed in claim 24, wherein the opening isan octangular shape in the plan view and the opening has a third lengthalong the first direction and a fourth length, which is different fromthe third length, along the second direction in the plan view.
 26. Thesemiconductor package as claimed in claim 18, wherein a ratio of thefirst length to the second length is between 46:45 and 99:54.